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File:Yellowing of thorium lenses.jpg

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Summary

Description
English: Some older photographic lenses were produced with glass elements containing small amounts of thorium. If stored in the dark for prolonged periods of time, these lenses can undergo what is commonly called “yellowing”. While some photographers enjoy the effect the yellowed glass has on their photographs (it acts similar to a weak yellow filter), others prefer to reverse it by exposing the lens to a UV light source.
  • left: a yellowed Super-Multi-Coated Takumar 50mm F1.4
  • center: an identical lens that had the same amount of yellowing, but was treated with a LED-based UV-emitting flashlight for several days until the yellowing almost disappeared.
  • right: an Auto Yashinon-DS 50mm f1.9 that showed no signs of yellowing for comparison
Please note: Not all lenses that appear yellow do so because of “yellowing” – many lens coatings do look golden/yellow/brown as well.
Date
Source Own work
Author El Grafo

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inception

4 January 2015

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Date/TimeThumbnailDimensionsUserComment
current13:09, 22 February 2015Thumbnail for version as of 13:09, 22 February 20154,734 × 1,702 (4.32 MB)El Grafominor background fix
17:20, 13 January 2015Thumbnail for version as of 17:20, 13 January 20154,734 × 1,702 (4.22 MB)El Grafomove that yashinon a bit to the right
16:24, 13 January 2015Thumbnail for version as of 16:24, 13 January 20154,676 × 1,702 (5.75 MB)El GrafoVicuñaUploader 1.20

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